4 5/12 - 5 3/5х = 2 2/3
5 3/5х = 4 5/12 - 2 2/3
5 3/5х = 4 5/12 - 2 8/12
5 3/5х = 3 17/12 - 2 8/12
5 3/5х = 1 9/12
5 3/5х = 1 3/4
28/5х = 7/4
х = 7/4 : 28/5
х = 7/4 * 5/28 = (1*5)/(4*4)
х = 5/16
Пояснения:
5 3/5 = (5*5+3)/5 = 28/5
1 3/4 = (1*4+3)/4 = 7/4